Abstract

Yeast Saccharomyces cerevisiae has five cyclin-dependent protein kinases (Cdks), Cdc28, Srb10, Kin28, Ctk1, and Pho85. Any of these Cdks requiresa cyclin partner for its kinase activity and a Cdk/cyclin complex, thus produced, phosphorylates a set of specific substrate proteins to exert its function. The cyclin partners of Srb10, Kin28, and Ctk1 are Srb11, Ccl1, and Ctk2, respectively. In contrast to the fact that each of Srb10, Kin28, and Ctk1 has a single cyclin partner, Cdc28 and Pho85 are polygamous; Cdc28 has 9 cyclins and Pho85 has 10 cyclins. Among these Cdks, Kin28 and Cdc28 are essential Cdks and it is well known that Cdc28 kinase plays a major role in regulating cell cycle progression. Pho85 is a non-essential Cdk but its absence causes a broad spectrum of phenotypes such as constitutive expression of PHO5, inability to utilize non-fermentable carbon sources, defects in cell cycle progression, and so on. Pho85 homologues are expanding to higher eukaryotes. Pho85 is most closely related with Cdk5 in terms of the amino acid sequence. The functional analysis of the domains of Pho85 also supports the close relationship between Pho85 and Cdk5, in which it was shown that the method of regulation of these two kinases is similar. Furthermore, forced expression of the mammalian CDK5 gene in a pho85Delta strain canceled a part of the pho85 defects. In this review, we summarize the functions of both Pho85/cyclin kinase and emphasize yeast Pho85 as valuable model systems to elucidate the functions of their homologues in other organisms.

Interaction Annotations

Increase the total number of rows showing on this page by using the pull-down located below the table, or use the
page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column
header to sort by that column; filter the table using the "Filter" box at the top of the table; click on the small
"i" buttons located within a cell for an annotation to view further details about experiment type and any other
genes involved in the interaction.

Gene Ontology Annotations

Increase the total number of rows showing on this page using the pull-down located below the table, or use the page
scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column header
to sort by that column; filter the table using the "Filter" box at the top of the table.

Phenotype Annotations

Increase the total number of rows showing on this page using the pull-down located below the table, or use the page
scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column header
to sort by that column; filter the table using the "Filter" box at the top of the table; click on the small "i"
buttons located within a cell for an annotation to view further details.

Regulation Annotations

Increase the total number of rows displayed on this page using the pull-down located below the table, or use the
page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column
header to sort by that column; to filter the table by a specific experiment type, type a keyword into the Filter box
(for example, “microarray”); download this table as a .txt file using the Download button or click Analyze to
further view and analyze the list of target genes using GO Term Finder, GO Slim Mapper, SPELL, or YeastMine.

Expression Datasets

Increase the total number of rows displayed on this page using the pull-down located below the table, or use the
page scroll at the table's top right to browse through the table's pages; use the arrows to the right of a column
header to sort by that column; filter the table using the "Filter" box at the top of the table; download this table
as a .txt file using the Download button;